Process for preparing modified ardealite by water-free calcining

Abstract

The invention relates to a method for preparing modified phosphogypsum through calcination without water scrubbing. The method is as follows: firstly, composite excitant and modifier are added into phosphogypsum and uniformly mixed, wherein, the weight percent of the phosphogypsum is between 85 and 95 percent; the weight percent of the composite excitant is between 2 and 5 percent; the weight percent of the modifier is between 3 and 10 percent; the composite excitant is green vitriol and aluminum sulphate, and the modifier is calcium oxide and cement; secondly, after uniform mixing, the mixture is dried at a drying temperature of between 100 and 110 DEG C, and the moisture of the phosphogypsum is lower than 8 percent; thirdly, the mixture enters into a calciner, is calcined for 0.5 to 1 hour at a temperature of between 150 and 300 DEG C, and is naturally cooled to prepare the modified phosphogypsum. The method decomposes and volatilizes harmful substances such as phosphor, fluorine, organic substances and so on contained in the phosphogypsum or converts the harmful substances into inert substance calcium pyrophosphate which is harmless to products, thereby not only avoiding secondary pollution but also reducing or avoiding influence of harmful chemical microconstituents contained in the phosphogypsum on the quality and the performance of the products. Moreover, the method shortens the processing time by 15 to 20 percent, saves the investment by 3 to 8 percent and reduces the energy consumption by 10 to 20 percent.

Description

technical field [0001] The invention relates to the technical fields of phosphorus chemical industry and building materials, and specifically describes a method for preparing modified phosphogypsum by calcining without water washing. Background technique [0002] Phosphogypsum is the industrial waste produced by the reaction of phosphate rock and sulfuric acid in the production process of wet-process phosphoric acid. It is calculated that every ton of phosphoric acid produced will produce 4-5 tons of phosphogypsum. At present, the annual discharge of phosphogypsum in the world reaches 200 million Tons, but the utilization rate of phosphogypsum is not more than 10%. The treatment, disposal and comprehensive utilization of phosphogypsum has become a worldwide problem. my country's phosphate fertilizer output ranks first in the world. The production of high-concentration phosphate fertilizers (such as ammonium phosphate, heavy calcium, etc.) requires a large amount of wet-proce...

AI Technical Summary

Problems solved by technology

[0009] The above-mentioned process has problems such as large one-time investment in pretreatment process, high energy consumption, serious secondary pollution of sewage discharge, etc., and the product lacks economic competitiveness.

A lot of work is still needed to fully promote the application